The present invention relates to a solids-free solution adapted for use as a well-servicing fluid and a method of use therefor.
A "clear brine fluid" is a solids free solution useful for servicing wells in the oil and gas industry, for example, as a well-completion, packer, workover and drilling fluid. In recent years clear brine fluids have been used in the oil and gas industry in place of drilling muds and solids-containing well-servicing fluids. Maintaining maximum formation permeability is better assured with solids-free well-servicing fluids and thus higher production rates are achieved.
Known clear brine fluids include, for example, zinc-containing brines such as solutions of zinc chloride and calcium chloride described in U. S. Pat. No. 3,126,950 and solutions of zinc bromide and calcium bromide described in U. S. Pat. Nos. 4,248,850; 4,292,183; 4,304,677 and 4,490,262. Such zinc-containing fluids typically have a density in excess of about fifteen pounds per gallon and typically may be more corrosive than non-zinc-containing brines. Because of the considerable cost in drilling and completing oil and gas wells, it is important that a desirable clear brine fluid exhibit a minimized, if any, significant corrosion rate toward the downhole metal tubular materials. Depending on the exposure time, this generally requires corrosion rates in the range of less than fifty mils per year. Downhole conditions can include a pressure of up to 20,000 psi and a temperature of about 400.degree. F. to 500.degree. F.
The clear brine fluids described in the prior art above may provide some corrosion protection, however, it is desired to minimize even further the corrosion rates of the fluids by providing the fluids with particular beneficial characteristics adapted to reducing the corrosion rate of such fluids.